Materials
Last Updated: 14th April 2009
Please do not read this page in isolation. In particular, be sure to read the Setup Page because as I discovered, any misalignment of the beam can have a dramatic effect on the machine's cutting power, and the Settings & Controls page as this gives some explanation of how the controls respond.
On this page I will describe my experiences with a number of different materials but what you see at the moment are merely my initial observations. I will update them as I gain experience.
Overview
We have three variables with which to approach any given material:
1. Beam power
2. Motor speed
3. Number of passes
I've said all I want to say about beam power and motor speed on the Settings & Controls page however I want to point out here that, because there is nothing touching the work piece other than a beam of light, it won't get moved and you can use 2 or more passes to cut something rather than trying to cut it in a single pass.
When material is cut, the width of the cut is greater on the top surface than on the bottom. With thin material this is hardly noticeable, but it is there. The slant is easier to observe with thicker material however this effect can be reduced by cutting the material with two or more passes. So multiple passes can improve the quality of the cut as well as increasing the thickness of material that can be cut.
Something else that's worth noting, is that unless the material has a tendency to shrink away from the beam, the width of cut is pretty consistent (assuming that the bed height is set correctly). Thus I have gotten into the habit of cutting shapes in cereal packet card in order to test fit and make adjustments to my drawing, before switching to a more expensive material e.g. acrylic, from which I want to make the actual item.
Acrylic
Acrylic and laser cutters seem made for each other but I've had it from a few sources and I'm finding that good stuff is expensive. The sheets I got from one supplier of hobby materials were bowed (which ain't gonna help with cutting), and some from another cut so strangely that I have my doubts that it was acrylic at all. The best stuff that I've tried so far came from an architectural model makers to whom I'm thinking of outsourcing some production runs. It was much stiffer, and more brittle than any of the other stuff I've had my hands on, but it cut beautifully.
I got some 2mm, 1mm, and 0.5mm stuff from them however the 1mm is 7 times (yes, seven) more expensive than the 2mm stuff so I won't be using a lot of that. I've found that for the 2mm stuff a single pass at speed=1, power=9.5 is not quite enough and that the best way to cut it is with speed=2, power=8, and do to passes.
I'll write about the 1mm and 0.5mm stuff when I've done more with it.
Cereal Packet Card
I always save this as it's a good model making material, and it's comes free with my breakfast cereal. It cuts nicely with speed=2, power=4.5 in a single pass.
I've got into the habit of using cereal packet card, to check that I've got everything right, before switching to acrylic or MDF for the actual item.
MDF
I've managed to obtain sheets of 1mm and 2mm thickness MDF from Hobbys.
The 1mm stuff cuts in a single pass with speed=2 and power=4, however to get through the 2mm stuff I need to bring the speed down to 1, even with power at 9.
The biggest problem I'm having is that it's rather smelly, and feels slightly sticky, after cutting. These effects go away after a few hours.
It also tends to leave a yellow residue which builds up on the cutting bed. However this is very easily removed with soap and warm water.
Plywood
I have not as yet been able to get my hands on "laser ply". I am told that it is different from normal plywood in that a different glue is used, which does not blacken when cut.
I have tried some ordinary 1.6mm ply from Hobbys however, in addition the the blackening, I found that speed=1, power=9 was not enough to cut cleanly and although two passes at speed=2, power=7 would do it, it tended to leave sooty marks on the surface.
In a nutshell, I could see no advantage in using this as opposed to MDF, especially when the MDF is about half the price.
Maybe that will change if/when I get my hands on some laser ply.